Network Working Group P. Eardley, Ed.
Request for Comments: 5559 BT
Category: Informational June 2009
Pre-Congestion Notification (PCN) Architecture
Status of This Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
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Abstract
This document describes a general architecture for flow admission and
termination based on pre-congestion information in order to protect
the quality of service of established, inelastic flows within a
single Diffserv domain.
Eardley Informational [Page 1]RFC 5559 PCN Architecture June 2009Table of Contents
1. Introduction ....................................................3
1.1. Overview of PCN ............................................3
1.2. Example Use Case for PCN ...................................4
1.3. Applicability of PCN .......................................7
1.4. Documents about PCN ........................................8
2. Terminology .....................................................9
3. High-Level Functional Architecture .............................11
3.1. Flow Admission ............................................13
3.2. Flow Termination ..........................................14
3.3. Flow Admission and/or Flow Termination When There Are Only
Two PCN Encoding States ...................................15
3.4. Information Transport .....................................16
3.5. PCN-Traffic ...............................................16
3.6. Backwards Compatibility ...................................17
4. Detailed Functional Architecture ...............................18
4.1. PCN-Interior-Node Functions ...............................19
4.2. PCN-Ingress-Node Functions ................................19
4.3. PCN-Egress-Node Functions .................................20
4.4. Admission Control Functions ...............................21
4.5. Flow Termination Functions ................................22
4.6. Addressing ................................................22
4.7. Tunnelling ................................................23
4.8. Fault Handling ............................................25
5. Operations and Management ......................................25
5.1. Fault Operations and Management ...........................25
5.2. Configuration Operations and Management ...................26
5.2.1. System Options .....................................27
5.2.2. Parameters .........................................28
5.3. Accounting Operations and Management ......................30
5.4. Performance and Provisioning Operations and Management ....30
5.5. Security Operations and Management ........................31
6. Applicability of PCN ...........................................32
6.1. Benefits ..................................................32
6.2. Deployment Scenarios ......................................33
6.3. Assumptions and Constraints on Scope ......................35
6.3.1. Assumption 1: Trust and Support of PCN -
Controlled Environment .............................36
6.3.2. Assumption 2: Real-Time Applications ...............36
6.3.3. Assumption 3: Many Flows and Additional Load .......37